Compassion Flood / Loving-Kindness

Compassion Flood — the sudden overwhelming arising of love, tenderness, or heart-opening compassion for a specific person, a whole category of beings, or (in its widest presentations) all sentient beings without exception — is one of the most-reported and most-durable positive-emotional dimensions of psychedelic and mystical experience, and one of the specific target-states of the Buddhist and other contemplative traditions.

In the Buddhist framework the state closely corresponds to mettā (loving-kindness, one of the four brahma vihāras or 'divine abodes' cultivated in meditation practice) and karuṇā (compassion). The classical Theravāda practice of mettā bhāvanā is explicitly designed to induce and cultivate this state through the systematic radiation of well-wishing outward, from oneself to a specific loved one, then to a neutral person, then to a difficult person, then to all beings. Contemporary secular adaptations (Compassion-Focused Therapy, the compassion cultivation programmes of the CCARE research group at Stanford) have documented substantial clinical benefits from the sustained practice.

MDMA (3,4-methylenedioxy-methamphetamine) has become the most-studied chemical route to a compassion-flood state; the specific serotonin- and oxytocin-mediated emotional opening it produces is close enough to the mettā-cultivated state that many contemplative practitioners have observed the correspondence. Contemporary MDMA-assisted psychotherapy for PTSD — currently in Phase 3 trials — works substantially through this specific emotional dimension: the ability to hold traumatic material within a heart-opened rather than defensively-armored state appears to be what allows the therapeutic reprocessing to occur.

Psilocybin and LSD produce compassion-flood states less predictably than MDMA but often more intensely when they arise. Experiencers commonly report sudden waves of unconditional love — for a specific person, for humanity, for suffering beings, for themselves — arriving unbidden and often with tears. The state is characteristically non-referential: unlike ordinary love, which is directed at a specific object, compassion flood is a background quality that then finds objects everywhere. Follow-up studies have consistently documented durable increases in measures of self-compassion, empathy, and prosocial behaviour after even single high-dose psilocybin sessions.

Sources:
Wikipedia — Loving-kindness meditation
Wikipedia — Karuṇā